In vehicles such as motor vehicles, in general, a fuel lid which covers a fuel filler port is attached to a vehicle body via a hinge so as to rotate about the hinge as a fulcrum to open and close in a front-to-rear direction. In addition, as an opening and closing apparatus for such a fuel lid, there is known an opening and closing apparatus including a pushrod for pushing a fuel lid in an opening direction. In this opening and closing apparatus, the pushrod is pushed in as a result of the fuel lid being pushed in a closing direction and is then held in the pushed-in position so as to close the fuel lid, and the pushrod is pushed out as a result of the fuel lid being pushed again so as to open the fuel lid (refer to W02008/059543A1 and US2009/0139991A1, for example).
An opening and closing apparatus described in WO2008/059543A1 includes a heart cam having a heart-shaped cam groove, a tappet which engages with the cam groove of the heart cam and a rocker which connects the tappet and a pushrod together, and a step is formed at a predetermined location in the cam groove. The tappet is moved in the cam groove as the pushrod is moved in a pushed-in direction, which is a direction in which the pushrod is pushed in, and a pushed-out direction, which is a direction in which the pushrod is pushed out, and is secured to the step portion in the cam groove to thereby hold the pushrod in a pushed-in position. Further, a lid securing portion for securing a fuel lid is provided at a distal end portion of the pushrod. The pushrod is rotated forwards a predetermined rotational angle (for example, 90°) about a center line while it is being shifted from a pushed-out position to the pushed-in position, whereby the pushrod brings the lid securing portion into engagement with the fuel lid to lock the fuel lid. In addition, the pushrod is rotated backwards the predetermined rotational angle about the center line while it is being shifted from the pushed-in position to the pushed-out position, whereby the lid securing portion is disengaged from the fuel lid to unlock the fuel lid.
An opening and closing apparatus described in US2009/0139991A1 includes a holder, which accommodates therein a pushrod, and a sleeve. The holder is provided with a first guide portion, which is made up of a plurality of inclined surfaces which are formed into a spiral shape. The pushrod is provided with a plurality of guide projections, which are adapted to individually engage with the inclined surface. The pushrod is rotated a predetermined rotational angle (for example, substantially 45°) in one direction by the first guide portion of the holder every time a fuel lid is pushed in. Further, the sleeve is provided with a second guide portion, which is made up of a plurality of long grooves and a plurality of shallow grooves formed and extended along the pushrod, and these long and shallow grooves are disposed alternately in a circumferential direction. In the pushrod, the group of guide projections is brought into engagement with the group of long grooves and the group of shallow grooves in an alternate fashion in response to a rotation made every time the fuel lid is pushed in. The fuel lid is held in a pushed-in position by bringing the group of guide projections into engagement with the group of shallow grooves. Further, the fuel lid is allowed to move towards a pushed-out position by bringing the group of guide projections into engagement with the group of long grooves.
In the opening and closing apparatus described in WO2008/0595431A1, the pushrod and the tappet are interlocked via the rocker, and the pushrod is held in the pushed-in position by securing the tappet, resulting in the complex mechanism. Due to this, it becomes difficult to reduce a size of the apparatus.
In the opening and closing apparatus described in US2009/0139991A1, although the apparatus is not configured such that the fuel lid is locked by using the pushrod, as with the opening and closing apparatus described in WO2008/059543A1, the opening and closing apparatus can be configured so that the lid securing portion is provided at the distal end portion of the pushrod which is rotated every time the fuel lid is pushed in so as to lock the fuel lid. In this case, the rotation of the pushrod made to engage the lid securing portion with the fuel lid or disengage the lid securing portion from the fuel lid is based on the engagement of the group of guide projections with the first guide portion and follows the rotation of the pushrod made to engage the group of guide projections with the group of long grooves and the group of shallow grooves of the second guide portion alternately.
Here, in a case where the rotational angle of the pushrod is small, a sufficient engagement margin between the fuel lid and the lid securing portion is not obtained, leading to fears that the locking strength becomes insufficient. In a case where the rotational angle of the pushrod is increased to ensure the engagement margin between the fuel lid and the pushrod, in relation to the length of the inclined surfaces of the first guide portion with respect to the moving direction of the pushrod, the gradient of the inclined surfaces becomes too moderate, resulting in fears that the proper movement and rotation of the pushrod is interrupted.
There are also fears that in a case where the pushing in of the fuel lid is interrupted halfway through a closing operation of the fuel lid, the pushrod is held in the pushed-in position without engaging the lid securing portion with the fuel lid. Then, when the fuel lid is opened, there are fears that the fuel lid pushed by the pushrod is forced to spring up to open.